At this point, we've spotted several thousand exoplanets - there's nothing super exciting any more about finding a distant star with several worlds orbiting it. But today, scientists are announcing that they have seen an exoplanet in the middle of forming.
Image of the new planet. The planet is the bright blob, and the black circle is a relic of the instrument that blocks the light from the central star. Image: ESO/A. Müller et al.
The dust disk of the star PDS 70 was detected by the Very Large Telescope's SPHERE and NAOS-CONICA instruments and the Gemini Near-Infrared Coronagraphic Imager, all located in Chile.
But after re-analysing data from the dust and taking further observations with SPHERE, scientists found what they were looking for: Robust evidence of a spot in the dust.
"Planets are born in circumstellar disks. These disks are made out of gas and dust and surround young stars until a lifetime of about 10 million years," graduate student Miriam Keppler from the Max Planck Institute for Astronomy in Germany told Gizmodo.
"The exciting fact of our discovery is that we have here an exceptionally robust detection of a young planet, still embedded in such a disk."
Scientists thought PDS 70 might have such a protoplanetary disk as early as 1992, and actually spotted the disk in 2006. Researchers have continued examining this region, most recently on February 24 of this year.
SPHERE blocks out the light from the star, allowing the researchers to observe the much-dimmer dust disk and planet at several wavelengths. The old and new data show the distinct presence of a planet, leaving a trail behind it - a gap in the disk.
Another analysis estimated that the nearly 1100C planet is somewhere between two and 17 times the mass of Jupiter, with a radius around 1.4 to 3.7 times Jupiter's. It's probably 5.4 million years old, and is orbiting PDS 70 at about 22 times the distance from the Earth to the Sun. It takes 118 Earth-years for this planet to make a full orbit around its star.
It's important to study these early planets in order to understand how planets form more generally.
"The measurement of the spectrum gives us insights on how planetary atmospheres look at a very early stage of life," said Keppler. "This is very important in order to calibrate theoretical models that predict the properties of planets as they evolve."
Of course, this research only just scratches the surface; there are plenty more planets and protoplanetary disks to study before we will ever fully comprehend the planetary formation process.
New telescopes such as the James Webb Space Telescope and the Atacama Large Millimetre/sub-millimetre Array could potentially help shine light (or, in this case, block out light) on this mysterious cosmic phenomenon.